Twin scroll turbocharger configurations may be used in turbocharged engines. A twin scroll turbocharger configuration may separate an inlet to a turbine into two separate passages connected to exhaust manifold runners so that exhaust from engine cylinders whose exhaust gas pulses may interfere with each other are separated.
For example, on an I4 engine with a cylinder firing order of 1-3-4-2, exhaust manifold runners 1 and 4 may be connected to a first inlet of a twin scroll turbine and exhaust manifold runners 2 and 3 may be connected to a second inlet of said twin scroll turbine, where the second inlet is different from the first inlet. Separating exhaust gas pulses in this way may, in some examples, result in an increase in efficiency of exhaust gas delivery to a turbine.
However, the inventors herein have recognized that under some engine operating conditions separating exhaust gas pulses as described above may reduce an efficiency of exhaust gas delivery to a turbine. For example, the inventors herein have recognized that under certain engine operating conditions, e.g., high speed and high load conditions, separating exhaust gas pulses as described above may result in an increase in backpressure and pumping work due to, for example, an increase in exhaust gas enthalpy.
In one example, the issues described above may be addressed by positioning a branch communication valve between a first scroll and a second scroll in a twin (e.g., dual) turbocharger scroll system. In one example, the first scroll and the second scroll may be fluidically separated by a dividing wall. A passage may be positioned vertically above the dividing wall and bridge the first scroll and the second scroll. The branch communication valve may be positioned within the passage. In an open position, exhaust flowing through the first and second scrolls may enter the passage and flow into the opposite scroll. In a closed position, the branch communication valve may seal against an opening between the passage and the first and the second scrolls, thereby reducing fluid communication between the scrolls.
In another example, a branch communication valve may be positioned within and/or adjacent to the dividing wall. The branch communication valve may be movable between an open and closed position. In a closed position, a portion of the branch communication valve may cover and seal against a hole or opening in the dividing wall. In an open position, the hole or opening may be exposed such that fluid communication between the first and second scrolls increases.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.